def print_models(unprinted_designs, completed_models):
    """
        模拟打印每个谁，直到没有未打印的涉及位置，
        打印每个设计后，都将其移动到列表 completed_models中
    """
    while unprinted_designs:
        current_desin = unprinted_designs.pop()
        print("\nPrinting model: " + current_desin)
        completed_models.append(current_desin)

def show_completed_models (completed_models):
    """ 显示打印好的所有模型 """
    print('\nThe following models have been printed: ')
    for completed_model in completed_models:
        print(completed_model)

unprinted_designs = ['iphone case', 'robot pendant', 'dodecahedron'] 
completed_models = []

print_models(unprinted_designs[:], completed_models)
show_completed_models(completed_models)
print(unprinted_designs, completed_models)